The Effect of a Host–Guest Hydrogen Bond on the Inclusion of Alcoholic Guests in the Host Cavities of Cholamide

Abstract

AbstractFifty eight inclusion crystals of cholamide (CAM) with aliphatic alcohols have been systematically investigated by X‐ray crystallography. The host frameworks of the inclusion crystals can be categorized into three structural types: bilayer, herringbone, and crossing structures. Most of the guests are included in bilayer structures, which can be further divided into four sub‐types. The host frameworks isomerize depending on the size and shape of the guest molecules. This dependence is clearly evaluated by the relationship between the volume of the guest molecules and the packing coefficient of the void space in the host frameworks. Although the host frameworks with the cavities and the structural isomerization are very similar to those of the inclusion crystals of cholic acid (CA), the inclusion behavior of aliphatic alcohols in the two hosts is completely different: fifty four alcohols can be included in the bilayer‐type structures of CAM, but only two in those of CA. This is attributed to their different functional groups, which lead to different hydrogen‐bond networks with the guest alcohols. The result in the two hosts is a good example to understand the effect of host–guest hydrogen bonds on guest inclusion in cavities that are identical in size and shape. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)